Hydraulic system and method for a hybrid vehicle

ABSTRACT

A hydraulic system for a hybrid module which is located between an engine and a transmission includes a parallel arrangement of a mechanical pump and an electric pump. Each pump is constructed and arranged to deliver oil to other portions of the hydraulic system depending on the operational mode. Three operational modes are described including an electric mode, a transition mode, and a cruise mode. Various monitoring and control features are incorporated into the hydraulic system.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of PCT Application No.PCT/US2012/025451, filed Feb. 16, 2012, which claims the benefit of U.S.Patent Application Ser. No. 61/443,750 filed Feb. 17, 2011, both ofwhich are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

With the growing concern over global climate change as well as oilsupplies, there has been a recent trend to develop various hybridsystems for motor vehicles. While numerous hybrid systems have beenproposed, the systems typically require significant modifications to thedrive trains of the vehicles. These modifications make it difficult toretrofit the systems to existing vehicles. Moreover, some of thesesystems have a tendency to cause significant power loss, which in turnhurts the fuel economy for the vehicle. Thus, there is a need forimprovement in this field.

One of the areas for improvement is in the construction and arrangementof the hydraulic system. Hybrid vehicles, and in particular the hybridmodule associated with such a vehicle, have various lubrication andcooling needs which depend on engine conditions and operational modes.In order to address these needs, oil is delivered by at least onehydraulic pump. The operation of each hydraulic pump is controlled,based in part on the lubrication and cooling needs and based in part onthe prioritizing when one or more hydraulic pump is included as part ofthe hydraulic system of the hybrid vehicle. The prioritizing betweenhydraulic pumps is based in part on the needs and based in part on theoperational state or mode of the hybrid vehicle.

SUMMARY

The hydraulic system (and method) described herein is part of a hybridmodule used within a hybrid system adapted for use in vehicles andsuitable for use in transportation systems and into other environments.The cooperating hybrid system is generally a self-contained andself-sufficient system which is able to function without the need tosignificantly drain resources from other systems in the correspondingvehicle or transportation system. The hybrid module includes an electricmachine (eMachine).

This self-sufficient design in turn reduces the amount of modificationsneeded for other systems, such as the transmission and lubricationsystems, because the capacities of the other systems do not need to beincreased in order to compensate for the increased workload created bythe hybrid system. For instance, the hybrid system incorporates its ownlubrication and cooling systems that are able to operate independentlyof the transmission and the engine. The fluid circulation system whichcan act as a lubricant, hydraulic fluid, and/or coolant, includes amechanical pump for circulating a fluid, along with an electric pumpthat supplements the workload for the mechanical pump when needed. Aswill be explained in further detail below, this dual mechanical/electricpump system helps to reduce the size and weight of the requiredmechanical pump, and if desired, also allows the system to run in acomplete electric mode in which the electric pump solely circulates thefluid.

More specifically, the described hydraulic system (for purposes of theexemplary embodiment) is used in conjunction with a hybrid electricvehicle (HEV). Included as part of the described hydraulic system is aparallel arrangement of a mechanical oil pump and an electric oil pump.The control of each pump and the sequence of operation of each pumpdepends in part on the operational state or the mode of the hybridvehicle. Various system modes are described herein relating to thehybrid vehicle. As for the hydraulic system disclosed herein, there arethree modes which are specifically described and these three modesinclude an electric mode (EMode), a transition mode, and a cruise mode.

As will be appreciated from the description which follows, the describedhydraulic system (and method) is constructed and arranged for addressingthe need for component lubrication and for cooling those portions of thehybrid module which experience an elevated temperature during operationof the vehicle. The specific construction and operationalcharacteristics provide an improved hydraulic system for a hydraulicmodule.

The compact design of the hybrid module has placed demands andconstraints on a number of its subcomponents, such as its hydraulics andthe clutch. To provide an axially compact arrangement, the piston forthe clutch has a recess in order to receive a piston spring that returnsthe piston to a normally disengaged position. The recess for the springin the piston creates an imbalance in the opposing surface areas of thepiston. This imbalance is exacerbated by the high centrifugal forcesthat cause pooling of the fluid, which acts as the hydraulic fluid forthe piston. As a result, a nonlinear relationship for piston pressure isformed that makes accurate piston control extremely difficult. Toaddress this issue, the piston has an offset section so that both sidesof the piston have the same area and diameter. With the areas being thesame, the operation of the clutch can be tightly and reliablycontrolled. The hydraulics for the clutch also incorporate a spill overfeature that reduces the risk of hydrostatic lock, while at the sametime ensures proper filling and lubrication.

In addition to acting as the hydraulic fluid for the clutch, thehydraulic fluid also acts as a coolant for the eMachine as well as othercomponents. The hybrid module includes a sleeve that defines a fluidchannel that encircles the eMachine for cooling purposes. The sleeve hasa number of spray channels that spray the fluid from the fluid channelonto the windings of the stator, thereby cooling the windings, whichtend to generally generate the majority of the heat for the eMachine.The fluid has a tendency to leak from the hybrid module and around thetorque converter. To prevent power loss of the torque converter, thearea around the torque converter should be relatively dry, that is, freefrom the fluid. To keep the fluid from escaping and invading the torqueconverter, the hybrid module includes a dam and slinger arrangement.Specifically, the hybrid module has a impeller blade that propels thefluid back into the eMachine through a window or opening in a dammember. Subsequently, the fluid is then drained into the sump so that itcan be scavenged and recirculated.

The hybrid module has a number of different operational modes. Duringthe start mode, the battery supplies power to the eMachine as well as tothe electric pump. Once the pump achieves the desired oil pressure, theclutch piston is stroked to apply the clutch. With the clutch engaged,the eMachine applies power to start the engine. During theelectro-propulsion only mode the clutch is disengaged, and only theeMachine is used to power the torque converter. In the propulsion assistmode, the engine's clutch is engaged, and the eMachine acts as a motorin which both the engine and eMachine drive the torque converter. Whilein a propulsion-charge mode, the clutch is engaged, and the internalcombustion engine solely drives the vehicle. The eMachine is operated ina generator mode to generate electricity that is stored in the energystorage system. The hybrid module can also be used to utilizeregenerative braking (i.e., regenerative charging). During regenerativebraking, the engine's clutch is disengaged, and the eMachine operates asa generator to supply electricity to the energy storage system. Thesystem is also designed for engine compression braking, in which casethe engine's clutch is engaged, and the eMachine operates as a generatoras well.

In addition, the system is also designed to utilize both power takeoff(PTO) and electronic PTO (ePTO) modes in order to operate ancillaryequipment such as cranes, refrigeration systems, hydraulic lifts, andthe like. In a normal PTO mode, the clutch and the PTO system areengaged, and the internal combustion engine is then used to power theancillary equipment. In an ePTO state, the clutch is disengaged and theeMachine acts as a motor to power the ancillary equipment via the PTO.While in the PTO or ePTO operational modes, the transmission can be inneutral or in gear, depending on the requirements.

Further forms, objects, features, aspects, benefits, advantages, andembodiments of the present invention will become apparent from adetailed description and drawings provided herewith.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a diagrammatic view of one example of a hybridsystem.

FIG. 2 illustrates a diagrammatic view of one hydraulic system suitablefor use in the FIG. 1 hybrid system.

FIG. 3 is a perspective, partial cross-sectional view of a hybridmodule-transmission subassembly.

FIG. 4 illustrates a diagrammatic view of the FIG. 2 hydraulic systemwhen the hydraulic system is in an eMode.

FIG. 5 illustrates a diagrammatic view of the FIG. 2 hydraulic systemwhen the hydraulic system is in a Transition Mode.

FIG. 6 illustrates a diagrammatic view of the FIG. 2 hydraulic systemwhen the hydraulic system is in a Cruise Mode.

FIG. 7 is a perspective view of the connection of a sump module assemblyto a hybrid module housing.

FIG. 8 is an exploded view of the FIG. 7 combination.

FIG. 9 is a perspective view of the sump module assembly with oilconnections shown.

FIG. 10 is an exploded view of the FIG. 9 sump module assembly.

FIG. 11 is an exploded view of the control module assembly illustratedin FIG. 10.

FIG. 12 is a perspective view of a main body which comprises one of thepanels of the FIG. 11 control module assembly.

FIG. 13A is a partial, front elevational view of the FIG. 7 combinationshowing a desired oil level.

FIG. 13B is a partial, side elevational view of the FIG. 7 combinationshowing the desired oil level.

FIG. 14 is an enlarged, diagrammatic view of a main regulator valvecomprising one portion of the FIG. 2 hydraulic system.

FIG. 15 is an enlarged, diagrammatic view of a control main valvecomprising one portion of the FIG. 2 hydraulic system.

FIG. 16 is an enlarged, diagrammatic view of a lube regulation valvecomprising one portion of the FIG. 2 hydraulic system.

FIG. 17 is an enlarged, diagrammatic view of a clutch trim system valvecomprising one portion of the FIG. 2 hydraulic system.

FIG. 18 is an enlarged, diagrammatic view of a main regulator by-passvalve comprising one portion of the FIG. 2 hydraulic system.

FIG. 19 is a rear elevational view of a solenoid body comprising aportion of the control module assembly illustrated in FIG. 10.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the disclosure,reference will now be made to the embodiments illustrated in thedrawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of thedisclosure is thereby intended, such alterations and furthermodifications in the illustrated device and its use, and such furtherapplications of the principles of the disclosure as illustrated thereinbeing contemplated as would normally occur to one skilled in the art towhich the disclosure relates.

FIG. 1 shows a diagrammatic view of a hybrid system 100 according to oneembodiment. The hybrid system 100 illustrated in FIG. 1 is adapted foruse in commercial-grade trucks as well as other types of vehicles ortransportation systems, but it is envisioned that various aspects of thehybrid system 100 can be incorporated into other environments. As shown,the hybrid system 100 includes an engine 102, a hybrid module 104, anautomatic transmission 106, and a drive train 108 for transferring powerfrom the transmission 106 to wheels 110. The hybrid module 104incorporates an electrical machine, commonly referred to as an eMachine112, and a clutch 114 that operatively connects and disconnects theengine 102 with the eMachine 112 and the transmission 106.

The hybrid module 104 is designed to operate as a self-sufficient unit,that is, it is generally able to operate independently of the engine 102and transmission 106. In particular, its hydraulics, cooling andlubrication do not directly rely upon the engine 102 and thetransmission 106. The hybrid module 104 includes a sump 116 that storesand supplies fluids, such as oil, lubricants, or other fluids, to thehybrid module 104 for hydraulics, lubrication, and cooling purposes.While the terms oil or lubricant or lube will be used interchangeablyherein, these terms are used in a broader sense to include various typesof lubricants, such as natural or synthetic oils, as well as lubricantshaving different properties. To circulate the fluid, the hybrid module104 includes a mechanical pump 118 and an electric pump 120 incooperation with a hydraulic system 200 (see FIG. 2). With this parallelcombination of the mechanical pump 118 and the electric pump 120, thereare opportunities to possibly reduce the overall size and perhaps thetotal cost for the pumps. The electric pump 120 cooperates with themechanical pump 118 to provide extra pumping capacity when required. Theelectric pump 120 is also used for hybrid system needs when there is nodrive input to operate the mechanical pump 118. In addition, it iscontemplated that the flow through the electric pump 120 can be used todetect low fluid conditions for the hybrid module 104.

The hybrid system 100 further includes a cooling system 122 that is usedto cool the fluid supplied to the hybrid module 104 as well as thewater-ethylene-glycol (WEG) to various other components of the hybridsystem 100. In one variation, the WEG can also be circulated through anouter jacket of the eMachine 112 in order to cool the eMachine 112.Although the hybrid system 100 has been described with respect to a WEGcoolant, other types of antifreezes and cooling fluids, such as water,alcohol solutions, etc., can be used. With continued reference to FIG.1, the cooling system 122 includes a fluid radiator 124 that cools thefluid for the hybrid module 104. The cooling system 122 further includesa main radiator 126 that is configured to cool the antifreeze forvarious other components in the hybrid system 100. Usually, the mainradiator 126 is the engine radiator in most vehicles, but the mainradiator 126 does not need to be the engine radiator. A cooling fan 128flows air through both fluid radiator 124 and main radiator 126. Acirculating or coolant pump 130 circulates the antifreeze to the mainradiator 126. It should be recognized that other various componentsbesides the ones illustrated can be cooled using the cooling system 122.For instance, the transmission 106 and/or the engine 102 can be cooledas well via the cooling system 122.

The eMachine 112 in the hybrid module 104, depending on the operationalmode, at times acts as a generator and at other times as a motor. Whenacting as a motor, the eMachine 112 draws alternating current (AC). Whenacting as a generator, the eMachine 112 creates AC. An inverter 132converts the AC from the eMachine 112 and supplies it to an energystorage system 134. In the illustrated example, the energy storagesystem 134 stores the energy and resupplies it as direct current (DC).When the eMachine 112 in the hybrid module 104 acts as a motor, theinverter 132 converts the DC power to AC, which in turn is supplied tothe eMachine 112. The energy storage system 134 in the illustratedexample includes three energy storage modules 136 that are daisy-chainedtogether to supply high voltage power to the inverter 132. The energystorage modules 136 are, in essence, electrochemical batteries forstoring the energy generated by the eMachine 112 and rapidly supplyingthe energy back to the eMachine 112. The energy storage modules 136, theinverter 132, and the eMachine 112 are operatively coupled togetherthrough high voltage wiring as is depicted by the line illustrated inFIG. 1. While the illustrated example shows the energy storage system134 including three energy storage modules 136, it should be recognizedthat the energy storage system 134 can include more or less energystorage modules 136 than is shown. Moreover, it is envisioned that theenergy storage system 134 can include any system for storing potentialenergy, such as through chemical means, pneumatic accumulators,hydraulic accumulators, springs, thermal storage systems, flywheels,gravitational devices, and capacitors, to name just a few examples.

High voltage wiring connects the energy storage system 134 to a highvoltage tap 138. The high voltage tap 138 supplies high voltage tovarious components attached to the vehicle. A DC-DC converter system140, which includes one or more DC-DC converter modules 142, convertsthe high voltage power supplied by the energy storage system 134 to alower voltage, which in turn is supplied to various systems andaccessories 144 that require lower voltages. As illustrated in FIG. 1,low voltage wiring connects the DC-DC converter modules 142 to the lowvoltage systems and accessories 144.

The hybrid system 100 incorporates a number of control systems forcontrolling the operations of the various components. For example, theengine 102 has an engine control module (ECM) 146 that controls variousoperational characteristics of the engine 102 such as fuel injection andthe like. A transmission/hybrid control module (TCM/HCM) 148 substitutesfor a traditional transmission control module and is designed to controlboth the operation of the transmission 106 as well as the hybrid module104. The transmission/hybrid control module 148 and the engine controlmodule 146 along with the inverter 132, energy storage system 134, andDC-DC converter system 140 communicate along a communication link as isdepicted in FIG. 1.

To control and monitor the operation of the hybrid system 100, thehybrid system 100 includes an interface 150. The interface 150 includesa shift selector 152 for selecting whether the vehicle is in drive,neutral, reverse, etc., and an instrument panel 154 that includesvarious indicators 156 of the operational status of the hybrid system100, such as check transmission, brake pressure, and air pressureindicators, to name just a few.

As noted before, the hybrid system 100 is configured to be readilyretrofitted to existing vehicle designs with minimal impact to theoverall design. All of the systems including, but not limited to,mechanical, electrical, cooling, controls, and hydraulic systems, of thehybrid system 100 have been configured to be a generally self-containedunit such that the remaining components of the vehicle do not needsignificant modifications. The more components that need to be modified,the more vehicle design effort and testing is required, which in turnreduces the chance of vehicle manufacturers adopting newer hybriddesigns over less efficient, preexisting vehicle designs. In otherwords, significant modifications to the layout of a preexisting vehicledesign for a hybrid retrofit require, then, vehicle and product linemodifications and expensive testing to ensure the proper operation andsafety of the vehicle, and this expense tends to lessen or slow theadoption of hybrid systems. As will be recognized, the hybrid system 100not only incorporates a mechanical architecture that minimally impactsthe mechanical systems of pre-existing vehicle designs, but the hybridsystem 100 also incorporates a control/electrical architecture thatminimally impacts the control and electrical systems of pre-existingvehicle designs.

Further details regarding the hybrid system 100 and its varioussubsystems, controls, components and modes of operation are described inProvisional Patent Application No. 61/381,614, filed Sep. 20, 2010,which is hereby incorporated by reference in its entirety.

Referring to FIG. 2, there is illustrated in diagrammatic form ahydraulic system 200 which is suitably constructed and arranged for usewith hybrid system 100. More particularly, hydraulic system 200 is aportion of hybrid module 104. Since the FIG. 2 illustration includescomponents which interface with a sump module assembly 202, broken lines204 are used in FIG. 2 to denote, in diagrammatic form, the functionallocations of the oil connections from other hydraulic components to thesump module assembly 202. Lower case letters are used in conjunctionwith reference numeral 204 in order to distinguish the various brokenline locations (204 a, 204 b, etc.). For example, the sump 116 is partof the sump module assembly 202, while mechanical pump 118 and electricpump 120 are not technically considered to be actual component parts ofthe sump module assembly 202, through this convention is somewhatarbitrary. The mechanical pump 118 and the electric pump 120 each havean oil connection with the sump module assembly 202. Sump 116 isindependent of the sump for the automatic transmission 106. Broken line204 a diagrammatically illustrates the location of flow communicationbetween the mechanical pump inlet conduit 206 and sump 116. Similarly,broken line 204 b denotes the location of flow communication between theelectric pump inlet conduit 208 and sump 116. Inlet conduit 206 definesinlet conduit opening 206 a. Inlet conduit 208 defines inlet conduitopening 208 a.

On the flow exiting sides of the two oil pumps, broken line 204 cdenotes the location where the outlet 210 of mechanical pump 118 is inflow connection (and flow communication with the sump module assembly202. Broken line 204 d denotes the location where the outlet 212 of theelectric pump 120 is in flow connection (and flow communication) withthe sump module assembly 202. This broken line convention is usedthroughout the FIG. 2 illustration. However, this convention is simplyfor convenience in explaining the exemplary embodiment and is notintended to be structurally limiting in any manner. While the othercomponents which have flow connections to the sump module assembly 202are not technically considered part of the sump module assembly, theseother components, such as the mechanical pump 118 and the electric pump120, are considered part of the overall hydraulic system 200.

With continued referenced to FIG. 2, hydraulic system 200 includes amain regulator valve 218, main regulator by-pass valve 220, control mainvalve 222, exhaust back fill valve 224, cooler 226, filter 228, lubesplitter valve 230, clutch trim valve 232, accumulator 234, solenoid236, and solenoid 238. It will be appreciated that these identifiedcomponent parts and subassemblies of hydraulic system 200 are connectedwith various flow conduits and that pop off valves are strategicallypositioned to safeguard against excessive pressure levels. Further,downstream from the lube splitter valve 230 are illustrated elementswhich are intended to receive oil. The first priority of the availableoil at the lube splitter valve 230 is for lubrication and cooling ofbearings 244 and gears or other accessories which are in need of coolingand lubrication. The second priority, once the first priority has beensatisfied, is to deliver oil to motor sleeve 246.

The mechanical pump 118 is constructed and arranged to deliver oil tothe main regulator valve 218 via conduit 250. One-way valve 248 isconstructed and arranged for flow communication with conduit 250 and ispositioned downstream from the mechanical pump 118. Valve 248 isconstructed and arranged to prevent backwards flow when the engine and(accordingly) the mechanical pump are OFF. Valve 248 includes a ball andspring arrangement set at a threshold of 5 psi. Branch conduits 252 and254 provide flow connections to the main regulator valve 218 and themain regulator by-pass valve 220, respectively. The electric pump 120 isconstructed and arranged to deliver oil to the main regulator by-passvalve 220 via conduit 256. The main regulator by-pass valve 220 is inflow communication with main regulator valve 218 via conduit 258, withcontrol main valve 222 via conduit 260, with clutch trim valve 232 viaconduit 262, with cooler 226 via conduit 264 and with solenoid 238 viaconduit 266.

The main regulator valve 218 is in flow communication with conduit 264via conduit 272. Conduit 274 is in flow communication with the mainregulator valve 218 and connects to conduit 276 which extends betweencontrol main valve 222 and solenoid 236. Branch conduit 278 establishesa flow path between conduit 274 and solenoid 238. Conduit 280establishes flow communication between main regulator valve 218 andclutch trim valve 232. Conduit 282 establishes flow communicationbetween control main valve 222 and exhaust back fill valve 224. Conduit284 establishes flow communication between exhaust back fill valve 224and clutch trim valve 232. Conduit 286 establishes flow communicationbetween clutch trim valve 232 and accumulator 234. Conduit 288establishes flow communication between clutch trim valve 232 and conduit276. Conduit 290 establishes flow communication between solenoid 236 andclutch trim valve 232. Conduit 292 establishes a flow path (main)between conduit 280 and control main valve 222. Conduit 294 establishesa control branch flow connection between conduit 276 and control mainvalve 222. Other flow connections and conduits are illustrated in FIG. 2and the corresponding flow path is readily apparent.

Considering the diagrammatic form of FIG. 2, it will be appreciated thatthe various flow connections and flow conduits may assume any one of avariety of forms and constructions so long as the desired oil flow canbe achieved with the desired flow rate and the desired flow timing andsequence. The hydraulic system 200 description makes clear what type ofoil flow is required between what components and subassemblies and theoperational reason for each flow path. The hydraulic system 200description which corresponds to what is illustrated in FIG. 2 isdirected to what components and subassemblies are in oil flowcommunication with each other, depending on the hybrid system 100conditions and the operational mode.

Before describing each of the three modes of operation applicable tohydraulic system 200, the relationship between and some of theconstruction details regarding the mechanical pump 118 and the electricpump 120 will be described. Understanding a few of the pump basicsshould facilitate a better understanding of the three modes of operationselected for further discussion regarding the overall hydraulic system.

Referring now to FIG. 3, a front perspective view is provided whichincludes a partial cross section through the hybrid module 104 from theperspective of the engine engagement side 300 of the hybrid module 104.On the engine engagement side 300, the hybrid module 104 has themechanical pump 118 with a pump housing 302 that is secured to thehybrid module housing 304. A pump drive gear 306 which is secured to aninput shaft 308 is used to drive the mechanical pump 118. The drive gear306 in one example is secured to the input shaft 308 via a snap ring andkey arrangement, but it is contemplated that the drive gear 306 can besecured in other manners. The mechanical pump 118 in conjunction withthe electric pump 120 supplies fluid for lubrication, hydraulics, and/orcooling purposes to the hybrid module 104. By incorporating the electricpump 120 in conjunction with the mechanical pump 118, it should bepossible for the mechanical pump 118 to be sized smaller, which in turnreduces the required space it occupies and should reduce the costassociated with the mechanical pump 118. Moreover, the electric pump 120facilitates lubrication even when the engine 102 is OFF. This in turnfacilitates electric-only operating modes as well as other modes of thehybrid system 100. Both the mechanical pump 118 and the electric pump120 recirculate fluid from the sump 116. The fluid is then supplied tothe remainder of the hybrid module 104 via holes, ports, openings andother passageways traditionally found in transmissions for circulatingoil and other fluids. A clutch supply port 310 supplies oil thathydraulically applies or actuates the clutch 114. In the illustratedembodiment, the clutch supply port 310 is in the form of a tube, but isenvisioned it can take other forms, such as integral passageways withinthe hybrid module 104, in other examples.

The operation of the hybrid system 100 involves or includes variousoperational modes or status conditions, also referred to herein as“system modes” or simply “modes”. The principal hybrid system 100 modesare summarized in Table 1 which is provided below:

TABLE 1 SYSTEM MODES Mode Clutch Motor PTO Transmission Engine StartEngaged Motor Inoperative Neutral Charge Neutral Engaged GeneratorInoperative Neutral eAssist Engaged Motor Inoperative In Gear PropulsioneDrive Disengaged Motor Inoperative In Gear Propulsion with EngagedGenerator Inoperative In Gear Charge Regeneration Disengaged GeneratorInoperative In Gear Charging No Charge Engaged N/A Inoperative In GearBraking PTO Engaged N/A Operative Neutral ePTO Disengaged MotorOperative Neutral

During an initialization and/or startup mode, the electric pump 120 isactivated by the transmission/hybrid control module 148 so as tocirculate fluid through the hybrid module 104. The electric pump 120receives its power from the energy storage system 134 via the inverter132 (FIG. 1). Once sufficient oil pressure is achieved, the clutch 114is engaged. At the same time or before, the PTO is inoperative orremains inoperative, and the transmission 106 is in neutral or remainsin neutral. With the clutch 114 engaged, the eMachine 112 acts as amotor and in turn cranks the engine 102 in order to start (i.e.,spin/crank) the engine. When acting like a motor, the eMachine 112 drawspower from the energy storage system 134 via the inverter 132. Upon theengine 102 starting, the hybrid system 100 shifts to a charge neutralmode in which the fuel is on to the engine 102, the clutch 114 isengaged, and the eMachine 112 switches to a generator mode in whichelectricity generated by its rotation is used to charge the energystorage modules 136. While in the charge neutral mode, the transmissionremains in neutral.

From the charge neutral mode, the hybrid system 100 can change to anumber of different operational modes. The various PTO operational modescan also be entered from the charge neutral mode. As should beunderstood, the hybrid system is able to move back and forth between thevarious operational modes. In the charge neutral mode, the transmissionis disengaged, that is, the transmission is in neutral. Referring toTable 1, the hybrid system 100 enters a propulsion assist or eAssistpropulsion mode by placing the transmission 106 in gear and having theeMachine 112 act as a motor.

During the eAssist propulsion mode, a PTO module is inoperative and thefuel to the engine 102 is on. In the eAssist propulsion mode, both theengine 102 and the eMachine 112 work in conjunction to power thevehicle. In other words, the energy to power the vehicle comes from boththe energy storage system 134 as well as the engine 102. While in theeAssist propulsion mode, the hybrid system 100 can then transition backto the charge neutral mode by placing the transmission 106 back intoneutral and switching the eMachine 112 to a generator mode.

From the eAssist propulsion mode, the hybrid system 100 can transitionto a number of different operational states. For instance, the hybridsystem 100 can transition from the eAssist propulsion mode to anelectrical or eDrive mode in which the vehicle is solely driven by theeMachine 112. In the eDrive mode, the clutch 114 is disengaged, and thefuel to the engine 102 is turned off so that the engine 102 is stopped.The transmission 106 is placed in a driving gear. As the eMachine 112powers the transmission 106, the PTO module is inoperative. While in theeDrive mode, the electric pump 120 solely provides the hydraulicpressure for lubricating the hybrid module 104 and controlling theclutch 114, because the mechanical pump 118 is not powered by thestopped engine 102. During the eDrive mode, the eMachine 112 acts as amotor. To return to the eAssist propulsion mode, the electric pump 120remains on to provide the requisite back pressure to engage the clutch114. Once the clutch 114 is engaged, the engine 102 is spun and fuel isturned on to power the engine 102. When returning to the eAssistpropulsion mode from the eDrive mode, both the eMachine 112 and theengine 102 drive the transmission 106, which is in gear.

The hybrid system 100 also has a propulsion charge mode, a regenerativebraking charge mode, and a compression or engine-braking mode. Thehybrid system 100 can transition to the propulsion charge mode from thecharge neutral mode, the eAssist propulsion mode, the regenerativebraking charge mode, or the engine-braking mode. When in the propulsioncharge mode, the engine 102 propels the vehicle while the eMachine 112acts as a generator. During the propulsion charge mode, the clutch 114is engaged such that power from the engine 102 drives the eMachine 112and the transmission 106, which is in gear. Again, during the propulsioncharge mode, the eMachine 112 acts as a generator, and the inverter 132converts the alternating current produced by the eMachine 112 to directcurrent, which is then stored in the energy storage system 134. In thismode, the PTO module is in an inoperative state. While in the propulsioncharge mode, the mechanical pump 118 generally handles most of the oilpressure and lubricant needs, while the electric pump 120 provideseMachine cooling. The load between the mechanical 118 and electric 120pumps is balanced to minimize power loss.

The hybrid system 100 can transition to a number of operational modesfrom the propulsion charge mode. For example, the hybrid system 100 cantransition to the charge neutral mode from the propulsion charge mode byplacing the transmission 106 in neutral. The hybrid system 100 canreturn to the propulsion charge mode by placing the transmission 106into gear. From the propulsion charge mode, the hybrid system 100 canalso switch to the propulsion assist mode by having the eMachine 112 actas an electric motor in which electricity is drawn from the energystorage system 134 to the eMachine 112 such that the eMachine 112 alongwith the engine 102 drive the transmission 106. The regenerative chargemode can be used to recapture some of the energy that is normally lostduring braking. The hybrid system 100 can transition from the propulsioncharge mode to the regenerative charge mode by simply disengaging theclutch 114. In some instances, it may be desirable to use theengine-braking mode to further slow down the vehicle and/or to reducewear of the brakes. Transitioning to the engine-braking mode can beaccomplished from the propulsion charge mode by turning off the fuel tothe engine 102. During the engine-braking mode, the eMachine 112 acts asa generator. The hybrid system 100 can return to the propulsion chargemode by turning back on the fuel to the engine 102. Simply disengagingthe clutch 114 will then switch the hybrid system 100 to theregenerative charging mode.

The hybrid system 100 is able to conserve energy normally lost duringbraking by utilizing the regenerative braking/charge mode. During theregenerative charge mode, the clutch 114 is disengaged. The eMachine 112acts as a generator while the transmission 106 is in gear. The powerfrom the wheels of the vehicle is transferred through the transmission106 to the eMachine 112, which acts as a generator to reclaim some ofthe braking energy and in turn helps to slow down the vehicle. Therecovered energy via the inverter 132 is stored in the energy storagesystem 134. As noted in Table 1 above, during this mode the PTO moduleis inoperative.

The hybrid system 100 can transition from the regenerative charge modeto any number of different operational modes. For instance, the hybridsystem 100 can return to the propulsion assist mode by engaging theclutch 114 and switching the eMachine 112 to act as a motor. From theregenerative charge mode, the hybrid system 100 can also return to thepropulsion charge mode by engaging the clutch 114, and switching theeMachine 112 to the generator role. The hybrid system 100 can alsoswitch to the engine-braking mode from the regenerative charge mode byturning off the fuel to the engine 102 and engaging the clutch.

In addition to the regenerative braking mode, the hybrid system 100 canalso utilize the engine-braking mode in which compression braking of theengine 102 is used to slow down the vehicle. During the engine brakingmode, the transmission 106 is in gear, the PTO module is inoperative,and the eMachine 112 is acting as a generator so as to recover some ofthe braking energy, if so desired. However, during other variations ofthe engine-braking mode, the eMachine 112 does not need to act as agenerator such that the eMachine 112 draws no power for the energy storesystem module 134. To transmit the energy from the vehicle's wheels, theengine clutch 114 is engaged and the power is then transmitted to theengine 102 while the fuel is off. In another alternative, a dualregenerative and engine braking mode can be used in which both theengine 102 and the eMachine 112 are used for braking and some of thebraking energy from the eMachine 112 is recovered by the energy storagesystem module 134.

The hybrid system 100 can transition from the engine-braking mode to anynumber of different operational modes. As an example, the hybrid system100 can switch from the engine-braking mode to the propulsion assistmode by turning on the fuel to the engine 102 and switching the eMachine112 to act as an electric motor. From the engine-braking mode, thehybrid system 100 can also switch to the propulsion charge mode byturning back on the fuel to the engine 102. In addition, the hybridsystem 100 can switch from the engine-braking mode to the regenerativecharge mode by turning on the fuel to the engine 102 and disengaging theclutch 114.

When the PTO is used, the vehicle can be stationary or can be moving(e.g., for refrigeration systems). From the charge neutral mode, thehybrid system 100 enters a PTO mode by engaging the PTO. While in thePTO mode, the clutch 114 is engaged such that power from the engine 102is transmitted to the now-operative PTO. During this PTO mode, theeMachine 112 acts as a generator drawing supplemental power from theengine 102 and transferring it via the inverter 132 to the energystorage system module 134. At the same time, the transmission 106 is inneutral so that the vehicle can remain relatively stationary, ifdesired. With the PTO operative, the ancillary equipment, such as thelift buckets, etc., can be used. The hybrid system 100 can return to thecharge neutral mode by making the PTO inoperative.

During the PTO mode, the engine 102 is constantly running which tends towaste fuel as well as create unnecessary emissions in some workscenarios. Fuel can be conserved and emissions reduced from the hybridsystem 100 by switching to an electric or ePTO mode of operation. Whentransitioning to the ePTO mode, the clutch 114, which transmits powerfrom the engine 102, is disengaged and the engine 102 is stopped. Duringthe ePTO mode, the eMachine 112 is switched to act as an electric motorand the PTO is inoperative. At the same time, the transmission 106 is inneutral and the engine 102 is stopped. Having the engine 102 turned offreduces the amount of emissions as well as conserves fuel. The hybridsystem 100 can return from the ePTO mode to the PTO mode by continuedoperation of the electric 120 pump, engaging the clutch 114 and startingthe engine 102 with the eMachine 112 acting as a starter. Once theengine 102 is started, the eMachine 112 is switched over to act as agenerator and the PTO is able to operate with power from the engine 102.

With the operation or system modes of hybrid system 100 (see Table 1) inmind, the hydraulic system 200 is now further described in the contextof three modes of operation. These three modes include an Electric Mode(eMode), a Transition Mode, and a Cruise Mode. From the perspective ofthe status and conditions of hydraulic system mode the eMode conditionsare diagrammatically illustrated in FIG. 4. The Transition Modeconditions are diagrammatically illustrated in FIG. 5. The Cruise Modeconditions are diagrammatically illustrated in FIG. 6.

Referring first to FIG. 4, in the eMode condition, as represented byhydraulic system 200 a, the engine and clutch are each in an “OFF”condition, and each solenoid 236 and 238 is an “OFF” condition. Theelectric pump 120 provides one hundred percent (100%) of the oil flow tothe main regulator valve 218. With solenoid 238 in an “OFF” condition,there is no solenoid signal to the main regulator by-pass valve 220 andthis component is also considered as being in an “OFF” condition. Themain pressure is “knocked down” to 90 psi due to using only the electricpump 120 and considering its performance limitations. Any lube/coolingflow to the cooler 226 is the result of main regulator valve 218overage.

Referring now to FIG. 5, in the Transition Mode condition as representedby hydraulic system 200 b, the engine may be in either an “ON” or “OFF”condition, the clutch is in an “ON” condition, solenoid 238 is “OFF”,and solenoid 236 is “ON”. The electric pump 120 and the mechanical pump118 can supply a flow of oil to the main regular valve 218. The mainpressure is knocked down to 90 psi and any lube/cooling flow to thecooler 226 is the result of main regulator valve 218 overage.

Referring now to FIG. 6, in the Cruise Mode, as represented by hydraulicsystem 200 c, the engine and clutch are each in an “ON” condition, andeach solenoid 236 and 238 is an “ON” condition. In this condition, themechanical pump 118 provides one hundred percent (100%) of the oil flowto the main regulator valve 218 and to the clutch control hydraulics.The electric pump 120 provides supplemental cooler flow (or what may bereferred to as cooler flow “boost”). The main pressure is at the“normal” (i.e., not knocked down) level of 205 psi. The flow to thecooler 226 is by way of the main regulator valve 218 overage andsupplemented by flow from the electric pump 120.

The three modes which have been described and illustrated in FIGS. 4-6have been identified in conjunction with hydraulic systems 200 a, 200 b,and 200 c, respectively. This numbering scheme of letter suffixes isrepresentative of the fact that the hardware, components, subassemblies,and conduits of hydraulic system 200 do not change with the differentmodes of operation. However, the operational status, the various ON/OFFconditions, etc. of the hardware, components, and subassemblies maychange, depending on the particular item and the specific mode ofoperation.

While the three described modes for the hydraulic system 200 are basedin part on the status or conditions of the engine, these modes are alsobased in part on the ON/OFF status of the referenced hardware,components, and subassemblies, including the mechanical pump 118 and theelectric pump 120. The mechanical pump 118 is directly connected to theengine 102 such that when the engine is ON, the mechanical pump 118 isON. When the engine 102 is OFF, the mechanical pump 118 is OFF. When ON,the mechanical pump 118 delivers oil to the entire hydraulic system. Anyoverage from the main regulator valve 218 is delivered to the cooler226.

The ON/OFF status of the electric pump 120 and the speed of the electricpump 120 are controlled by the electronics of the hybrid module 104. Theelectric pump 120 delivers oil either to the hydraulic system 200 and/orto the cooler 226. When the mechanical pump 118 is either OFF or whenits delivery of oil is insufficient, the electric pump 120 delivers oilto the hydraulic system. When the delivery of oil from the mechanicalpump is sufficient, the electric pump 120 is able to be used fordelivery of oil to the cooler for lube and motor cooling.

Reference has been made to the knocked down lower pressure level forcertain operational modes. This knocked down pressure is associated withoperation of the electric pump 120. Considering the various pressurelevels and flow rates, the main pressure of the mechanical pump 118 is205 psi. The main pressure of the electric pump 120 is 90 psi. For lubeand cooling, the first 5.0 lpm of flow at approximately 30 psi is usedfor lube. Any excess flow up to approximately 15.0 lpm is delivered tothe motor cooling sleeve 246. A maximum of 50 psi for the lube/coolingfunction is attained only after the motor cooling sleeve 240 is filledwith oil. The clutch applied pressure is 205 psi nominal (1410 kPa) and188 psi minimum (1300 kPa).

Referring now to FIGS. 7 and 8, the arrangement of the sump moduleassembly 202 relative to the hybrid module housing 304 is illustrated asconnected (FIG. 7) and as an exploded view (FIG. 8). Further illustratedas part of the FIG. 7 assembly are the low voltage electric connection322, a fluid port 324 for connecting to the cooler 226, a fluid port 326for connection from the cooler 226 and post-cooler filter 228. The sumpmodule assembly 202 is securely attached beneath the hybrid modulehousing 304 using a series of threaded fasteners 328. The exploded viewof FIG. 8 illustrates some of the internal components of the sump moduleassembly 202 and the layout of these internal components. The details ofthe sump module assembly are described hereinafter with reference toother drawings.

Referring now to FIGS. 9-12, further details regarding the sump moduleassembly 202 are illustrated. In FIG. 9, the various oil connections arecalled out. These include the electric pump pressure connection 334 andthe electric pump suction connection 336. Similarly, the mechanical pumppressure connection 338 and the mechanical pump suction connection 340are identified. Further included is the housing lube connection 342, themotor cooling connection 344, the clutch feed connection 346, and thecooler return connection 348. The oil level sensor 350, as assembledinto the sump module assembly 202, is also illustrated.

Referring to FIG. 10, there is an exploded view of the sump moduleassembly 202 showing the control module assembly 356 as separated fromthe sump body 358. The sump body 358 is preferably a casting with alower surface 360 and integral sidewalls 362 so as to provide a closedreceptacle or interior volume for oil.

Referring to FIG. 11, the control module assembly 356 is illustrated asan exploded view showing the three layers, including a solenoid body366, a separator plate 368, and a main body 370. These three plate orpanel-like layers are constructed and arranged and securely joinedtogether in order to create the necessary mechanical and hydraulicconnections, the desired flow paths, and compartments for the receipt ofoperational components.

The solenoid body 366 includes a plurality of separately definedhydraulic compartments 372. In this regard it should be noted that theunderside or opposite side of solenoid body 366 is not fully shown inthe FIG. 11 illustration. It will be understood that the illustratedhydraulic compartments 372 are closed off in part by the bottom panel366 a of the solenoid body 366, as illustrated in FIG. 19. This bottomor back panel 366 a is constructed and arranged with componentcompartments as described in connection with FIG. 19. The flow into andout of each hydraulic compartment 372 is affected and controlled, atleast in part, by the pattern of apertures 374 defined by separatorplate 368 and to a further extent by the construction and arrangement ofmain body 370. As will be appreciated, the solid portions or areas ofthe separator plate 368 are constructed and arranged to close off orcover over portions of the hydraulic compartments 372. In this way, flowinto and through one or more of the hydraulic compartments is enabled,consistent with the construction and intended operation of the hydraulicsystem 200 disclosed herein.

Referring now to FIG. 12, additional structural details of main body 370are illustrated. As described, there are compartments for receipt ofother operational components. While these other operational componentsmay be purchased, readily-available parts, they may also be originallymanufactured or custom manufactured parts, depending on the specificoperational modes and parameters desired for hydraulic system 200. Inthe construction of main body 370, a compartment 378 is provided forreceipt of a mechanical pump pop-off valve 380 (see FIG. 1). Compartment382 is provided for receipt of the main regulator valve 218. Compartment384 is provided for receipt of the control main valve 222. Compartment386 is provided for the receipt of lube splitter valve 230. Compartment388 is provided for receipt of a cooler pop-off valve 390 (see FIG. 1).Additionally, main body 370 includes various hydraulic connectors andfittings, consistent with the construction and intended operation ofhydraulic system 200, as disclosed herein.

Pop-off valves 380 and 390 are similarly constructed with a ball, valveseat, and biasing spring. The mechanical pump pop-off valve 380 has aset point of 400 psi. The cooler pop-off valve 390 has a set point of140 psi.

Referring to FIGS. 13A and 13B, the assembled combination of the sumpmodule assembly 202 and the hybrid module housing 304 (see FIG. 7) isillustration in partial form as a front elevational view and as a sideelevational view. Each view includes a broken line 392 which denotes thedesired oil level.

Referring now to FIG. 14, an enlarged diagrammatic illustration of themain regulator valve 218 is provided. As illustrated in FIG. 2, flowconduits 250, 252, 258, 272, 274, and 280 connect directly to mainregulator valve 218. Conduit 272 is constructed and arranged to delivera lube and cooling flow to the cooler 226. Conduit 274 is constructedand arranged to deliver a control flow to solenoids 236 and 238 and toclutch trim valve 232. Conduit 280 is constructed and arranged todeliver the main flow to control main valve 222 and to clutch trim valve232. Conduit 252 is constructed and arranged to provide main feedbackinto conduit 250. Conduit 258 is constructed and arranged to connect tothe main regulator by-pass valve 220. Conduit 250 is constructed andarranged to deliver the main flow into main regulator valve 218 from themechanical pump 118.

The main regulator valve 218 is a dual regulation valve which operatesin the range of 205 psi without knockdown and approximately 90 psi withknockdown. Any flow overage is sent to the cooler 226. The secondregulation point goes to exhaust. Conduit 252 includes a feedbackorifice 252 a of approximately 1.0 mm.

Referring now to FIG. 15, an enlarged diagrammatic illustration of thecontrol main valve 222 is provided. As illustrated in FIG. 2, flowconduits 260, 276, 282, 292, and 294 connect directly to control mainvalve 222.

Conduit 260 is constructed and arranged to connect between the controlmain valve 222 and the main regulator by-pass valve 220. Conduit 282connects the control main valve 222 to the exhaust back fill valve 224.Conduit 292 is constructed and arranged to deliver the main flow tocontrol main valve 222 from main flow conduit 280. Control conduit 276connects to solenoid 236 and to clutch trim valve 232 by way of conduit290 for a control flow of oil. Conduit 288 connects the control mainvalve 222 to pressure switch 414. Control feedback to control main valve222 is provided by conduit 294.

The control main valve 222 operates in the pressure regulation range ofapproximately 110 psi. Any flow overage is sent to the exhaust back fillvalve 224. The feed orifice 292 a in conduit 292 is approximately 3.0mm. The feedback orifice 294 a in conduit 294 is approximately 1.0 mm.When the pressure knock down is present (i.e., activate), the controlmain valve 222 acts as a flow pass through. At 90 psi, the flow isregulated by the main regulator valve 218.

Referring now to FIG. 16, an enlarged diagrammatic illustration of thelube regulation valve 230 is provided. As illustrated in FIG. 2, luberegulation valve 230 is positioned between the upstream filter 228 andthe downstream motor sleeve 246 and bearing locations 244, as well asrelated components which require priority lube and cooling. Conduit 400provides the flow connection between the filter 228 and the luberegulation valve 230. Branch conduit 402 provides lube feedback. Conduit404 establishes a flow connection between the motor sleeve 246 and thelube regulation valve 230. Conduit 406 establishes a flow connectionbetween those downstream components, such as bearings, which requirelube and cooling, and the lube regulation valve 230.

The lube regulation valve 230, also referred to functionally as a lubesplitter valve, is a dual regulation valve. The initial flow (onehundred percent (100%)) at 5.0 lpm goes to the lube requirements of thebearings 244 and related downstream components via conduit 406. Atapproximately 32 psi, the second flow path to the motor sleeve 246 opensvia conduit 404, providing additional oil flow for motor cooling. If themotor sleeve 246 is plugged or otherwise blocked, the valve exhausts theflow at 48 psi. The feedback orifice 402 a is approximately 1.0 mm.

Referring now to FIG. 17, an enlarged diagrammatic illustration of aclutch trim system 410 is provided. Clutch trim system 410 includesclutch trim valve 232, the associated flow conduits, exhaust controls,and the input clutch 412. The conduit connections to solenoid 236 andaccumulator 234 are included. Conduit 284 is constructed and arrangedfor flow connection between the clutch trim valve 232 and the exhaustbackfill valve 224 for the exhaust backfill feed. The main feed isprovided by way of conduit 280 which is constructed and arranged forflow communication between the clutch trim valve 232 and the mainregulator valve 218. Pressure switch and latch input 414 is provided byway of the pressure level of the control flow in conduit 262 andconnecting conduit 416. The input clutch 412 is in main flow connectionwith the clutch trim valve 232 by way of common conduits 418 and 420.

The clutch trim system 410 includes solenoid 236 which is a “normallyhigh” solenoid and described functionally as a “trim” solenoid. The gainis approximately 2.83. The pressure switch 414 flips before the clutchopens to main. The regulation points include nominal, which is full mainplus 15 psi, and worst case, which is approximately 190 psi. The mainfeed orifice 280 a is approximately 4.0 mm. Clutch feed orifice 418 a isapproximately 3.0 mm. The feedback orifice 420 a is approximately 1.0mm.

Referring to FIG. 18, an enlarged diagrammatic illustration of the mainregulator by-pass valve 220 is provided. As illustrated in FIG. 2, flowconduits 254, 256, 258, 260, 262, 264, and 266 are in direct connectionwith main regulator by-pass valve 220. Conduit 254 connects to conduit250 which carries the main flow from the mechanical pump 118. Conduit256 is in flow communication with the electric pump 120. Conduit 258 isconstructed and arranged for connection to main regulator valve 218 inorder to establish a control flow therebetween sensed by a pressureswitch. This conduit provides the knock down signal. Conduit 260 isconstructed and arranged for connection to the exhaust backfill valve224. Conduit 262 is constructed and arranged for flow connection toconduit 416 and pressure sensing by pressure switch 414. The flow by wayof conduit 262 to the clutch trim valve 232 provides a latch signal.Conduit 264 is constructed and arranged for flow connection to cooler226. Conduit 266 is constructed and arranged for flow connection tosolenoid 238.

The main regulator by-pass valve 220 is used to direct the flow of oilfrom the electric pump 120. This valve also controls the knock down(i.e., reduced pressure). As installed, valve 220 controls the electricpump output to the main regulator valve by way of conduits 256 and 254.The knock down is active and the latch area is exhausted. In the applied(ON) position, the electric pump output is directed to the cooler 226,the knock down is exhausted, and the latch is active with the inputclutch 412. With the main regulator by-pass valve down, the valvelatches during a POWER OFF status and provides full clutch capacity.

The exhaust backfill valve 224 has a pressure set point of 2 psi. Theflow circuit associated with valve 224 feeds the control main valveoverage and the wasting pressure switches. The bleed orifice fromcontrol main valve is approximately 1.0 mm.

With reference now to FIG. 19, the back panel 366 a portion of solenoidbody 366 is illustrated with the assembly of various component partstherein. Included and assembled into receiving locations andcompartments is the clutch trim valve 232, the trim solenoid 236, theexhaust backfill valve 224, the ON/OFF solenoid 238 for the mainregulator by-pass valve 220, the main regulator by-pass valve 220, andthe one-way valve 248. Also illustrated as part of pack panel 366 a is aconnection port 426 for the electric pump and pressure switches 428 and414.

The basics of the hydraulic system 200 construction and theconfiguration having been illustrated and described, additional detailsregarding the component status and use, the various flows, and thecontrol signals will now be provided relative to each of the three modesidentified above.

Table 2 provides a brief summary of each mode in terms of the hydraulicstatus or conditions relative to the vehicle.

TABLE 2 Engine State Electric Logic Valve Electric (Mechanical Pump(MRBV) Clutch Trim Pump Mode Pump State) State State Valve State toSupply Clutch State Electric OFF ON INSTALLED INSTALLED MAIN OPENPRESSURE Transition OFF --> ON ON INSTALLED INSTALLED --> MAIN OPEN -->APPLIED PRESSURE APPLIED Cruise ON ON or APPLIED APPLIED TO COOLERAPPLIED OFFElectric Mode (eMode):

This mode is defined by a steady state of engine off, clutch open, andelectric pump on. Vehicle modes available are: Electric propulsion,Electric PTO mode, ReGen (engine off), etc.

In electric mode, the clutch is open therefore the engine is notconnected to the transmission so therefore, torque from the sandwich tothe transmission is created by the electric motor. Hydraulically, allflow and pressure is provided by the electric pump. The electric pumpcreates flow that flows through the MRBV to the main regulator valve.From here the hydraulic circuit and leak paths are satisfied first andthe additional flow is sent to the cooler and returns to the lube valvewhich directs the “from cooler” oil to either lube for the housing orcooling for the motor.

The main regulator valve has a knockdown in operation so the pressureregulates at 90 psi. The knockdown is paired with the MRBV position(MRBV installed=knockdown applied, MRBV applied=knockdown unapplied) andis designed to prevent the electric pump from over pressurizing (whichreduces max electric pump power requirements).In this mode the electric pump is providing a flow at 90 psi ofpressure.Transition Mode:

This hydraulic mode encompasses a wide variety of transitional vehiclestates. This state is principally defined as the ePump supplying themain regulator valve and the clutch applied. The mechanical pump can beeither ON or OFF (depending upon engine state). Both pumps 118 and 120supplying the main regulator valve means that the knockdown is stillapplied and the ePump is making flow at 90 psi of pressure. This alsolimits the clutch to 90 psi, limiting the amount of engine torque thatcan be transferred through the sandwich module.

Hydraulically, cooler flow, lube, and motor cooling are all provided inthe same manner as in Electric Mode.

From a vehicle standpoint, this mode is used when transitioning fromEngine off/Clutch off to Engine On/Clutch On. This mode is not optimalfor idle or cruise of the vehicle and therefore is used only as atransition between eMode and Cruise Mode.

Cruise Mode:

This mode is defined as engine on, clutch applied & ePump output flowingto the cooler (by-passing the main regulator valve). The modeencompasses any vehicle state in which the vehicle is in idle or motionand the engine (with or without assistance from eMotor) is providingtorque to the input of the transmission.

The mechanical pump flows directly to the main regulator valve(knockdown off) which regulates to a high pressure (210 psi). The logicvalve is in the applied position which exhausts the knockdown (shuttingit off) and also directing the ePump's flow to by-pass the mainregulator and flow directly to the cooler/lube circuit.

Hydraulically, the cooler/lube/motor cooling circuits are also suppliedby overage from the main regulator valve.

From a vehicle standpoint, the clutch is applied and the engine torqueis transferred through the clutch to the input of the transmission. Inthis mode, the eMotor can provide or absorb torque (ReGen) to/from theinput of the transmission or can be shut off, effectively making thevehicle a non-hybrid.

Table 3 lists the pressure set points for the various valves and pop-offvalves. The main regulator valve is listed with and without knockdown.

TABLE 3 Pressure Set Points Valve Pressure (psi) Pressure (kPa) MainRegulator w/o Knockdown 206 1418 Main Regulator w/ Knockdown 90 618Control Main 110 762 Lube -Sleeve Opening 32 224 Lube - Exhaust (maxpress) 48 329 Mechanical pop-off 400 2759 Cooler pop-off 141 970 By-PassLatch 50 343Filter 228 is constructed and arranged to handle the cooler return andis ninety-eight percent (98%) efficient at 32 microns. There is aninternal pop-off valve structure. The suction pick up is centrallylocated at the sump floor.

TABLE 4 Flow Requirements State 1 State 2 Clutch open Clutch engagedEngine off Engine running Flow (lpm) Flow (lpm) Motor cooling 8.5 8.5Based on study and (110 C.) modeling Motor cooling 14 14 Based on studyand (120 C.) modeling Clutch lube 2.5 2.5 BOD-300 Ball-bearing lube 1.21.2 Bearing supplier (x3) recommendation Balance leakage 1 1 Clutchapply bleed 1.3 2 Misc lube 1 1 Splines, thrust bearings, etc. Controlsleakage 2 3 Valves and solenoids Total (110 C.) 17.5 19.2 Total (120 C.)23 24.7 E-pump pressure 90 50 (psi) M-pump pressure 0 210 (psi)The main regulator valve 218, main regulator by-pass valve 220, controlmain valve 22, exhaust backfill valve 224, lube regulator valve 230, andclutch trim valve 232 each have a construction and arrangement whichcould be described, based on its construction and functionality, as a“spool valve”. Each valve includes a valve body which defines aninterior valve bore. Each valve also includes the use of a valve spoolwhich is slidably disposed within the valve bore of the valve body. Theselected cylindrical lands can be varied by diameter size, axial height,spacing, and relative location along the axis of the valve spool. Thevalve bore can also include sections with different diameters. Flowpassages defined by the valve body connect to the various conduits,providing a predetermined and preselected arrangement of flow inputs andoutputs, depending on incoming pressure levels and the positioning ofthe valve spool relative to the various flow passages. A more detaileddescription of this type of spool valve is provided in U.S. Pat. Nos.7,392,892; 7,150,288; and 5,911,244. These three U.S. patent referencesare hereby incorporated by reference in their entirety as backgroundtechnical information on the style and type of valve being used.

While the preferred embodiment of the invention has been illustrated anddescribed in the drawings and foregoing description, the same is to beconsidered as illustrative and not restrictive in character, it beingunderstood that all changes and modifications that come within thespirit of the invention are desired to be protected.

The invention claimed is:
 1. A hydraulic system for a hybrid electricvehicle comprising: a sump containing hydraulic fluid; a main regulatorvalve; a main regulator by-pass valve, which is in direct fluidcommunication with said main regulator valve; a mechanical pumpconstructed and arranged in fluid communication with said sump and indirect fluid communication with said main regulator valve for deliveringhydraulic fluid directly from said sump to said main regulator valve; anelectric pump constructed and arranged in fluid communication with saidsump and in direct fluid communication with said main regulator by-passvalve for delivering hydraulic fluid directly from said sump to saidmain regulator by-pass valve; a controller for controlling theoperational status of each pump based on an operational mode of thehybrid electric vehicle; a clutch trim valve; a first control solenoidconstructed and arranged in fluid communication with said main regulatorby-pass valve; a second control solenoid constructed and arranged influid communication with said clutch trim valve; wherein the hybridelectric vehicle has three operational modes associated with thehydraulic system, including an eMode, a transition mode and a cruisemode; and wherein said first control solenoid and second controlsolenoid each have an operational condition which is determined by whichof the three operational modes represents the operational mode of thehybrid electric vehicle.
 2. A hydraulic system for a hybrid electricvehicle comprising: a sump containing hydraulic fluid; a main regulatorvalve; a main regulator by-pass valve; a mechanical pump constructed andarranged in fluid communication with said sump and in direct fluidcommunication with said main regulator valve for delivering hydraulicfluid directly from said sump to said main regulator valve; an electricpump constructed and arranged in fluid communication with said sump andin direct fluid communication with said main regulator by-pass valve fordelivering hydraulic fluid directly from said sump to said mainregulator by-pass valve, wherein the hybrid electric vehicle has threeoperational modes associated with the hydraulic system, including aneMode, a transition mode and a cruise mode; and wherein when said hybridelectric vehicle is in said eMode, the first control solenoid is in anOFF operational condition and said second control solenoid is in an OFFoperational condition.
 3. The hydraulic system of claim 2 wherein whensaid hybrid electric vehicle is in said eMode, all of the hydraulicfluid which is delivered from the sump to any of the valves of thehydraulic system is delivered by said electric pump.
 4. A hydraulicsystem for a hybrid electric vehicle comprising: a sump containinghydraulic fluid; a main regulator valve; a main regulator by-pass valve;a mechanical pump constructed and arranged in fluid communication withsaid sump and in direct fluid communication with said main regulatorvalve for delivering hydraulic fluid directly from said sump to saidmain regulator valve; an electric pump constructed and arranged in fluidcommunication with said sump and in direct fluid communication with saidmain regulator by-pass valve for delivering hydraulic fluid directlyfrom said sump to said main regulator by-pass valve, wherein the hybridelectric vehicle has three operational modes associated with thehydraulic system, including an eMode, a transition mode and a cruisemode; and wherein when said hybrid electric vehicle is in saidtransition mode, said first control solenoid is in an OFF operationalcondition and said second control solenoid is in an ON operationalcondition.
 5. The hydraulic system of claim 4 wherein when said hybridelectric vehicle is in said transition mode, the hydraulic fluid whichis delivered from the sump to any of the valves of the hydraulic systemis delivered in apportioned amounts by said electric pump and by saidmechanical pump.
 6. A hydraulic system for a hybrid electric vehiclecomprising: a sump containing hydraulic fluid; a main regulator valve; amain regulator by-pass valve; a mechanical pump constructed and arrangedin fluid communication with said sump and in direct fluid communicationwith said main regulator valve for delivering hydraulic fluid directlyfrom said sump to said main regulator valve; and an electric pumpconstructed and arranged in fluid communication with said sump and indirect fluid communication with said main regulator by-pass valve fordelivering hydraulic fluid directly from said sump to said mainregulator by-pass valve, wherein the hybrid electric vehicle has threeoperational modes associated with the hydraulic system, including aneMode, a transition mode and a cruise mode; and wherein said hybridelectric vehicle is in said cruise mode, said first control solenoid isin an ON operational condition and said second control solenoid is in anON operational condition.
 7. The hydraulic system of claim 6 whereinwhen said hybrid electric vehicle is in said cruise mode, all of thehydraulic fluid which is delivered from the sump to any of the valve ofthe hydraulic system is delivered by said mechanical pump.
 8. Ahydraulic system for a hybrid electric vehicle comprising: a sumpcontaining hydraulic fluid; a main regulator valve; a main regulatorby-pass valve; a mechanical pump constructed and arranged in fluidcommunication with said sump and in fluid communication with said mainregulator valve for delivering hydraulic fluid from said sump to saidmain regulator valve; and an electric pump constructed and arranged influid communication with said sump and in fluid communication with saidmain regulator by-pass valve for delivering hydraulic fluid from saidsump to said main regulator by-pass valve, wherein the hybrid electricvehicle has three operational modes associated with the hydraulicsystem, including an eMode, a transition mode and a cruise mode, whereinwhen said hybrid electric vehicle is in said eMode, the first controlsolenoid is in an OFF operational condition and said second controlsolenoid is in an OFF operational condition.
 9. The hydraulic system ofclaim 8 wherein when said hybrid electric vehicle is in said eMode, allof the hydraulic fluid which is delivered from the sump to any of thevalves of the hydraulic system is delivered by said electric pump.
 10. Ahydraulic system for a hybrid electric vehicle comprising: a sumpcontaining hydraulic fluid; a main regulator valve; a main regulatorby-pass valve; a mechanical pump constructed and arranged in fluidcommunication with said sump and in fluid communication with said mainregulator valve for delivering hydraulic fluid from said sump to saidmain regulator valve; and an electric pump constructed and arranged influid communication with said sump and in fluid communication with saidmain regulator by-pass valve for delivering hydraulic fluid from saidsump to said main regulator by-pass valve, wherein the hybrid electricvehicle has three operational modes associated with the hydraulicsystem, including an eMode, a transition mode and a cruise mode, whereinwhen said hybrid electric vehicle is in said transition mode, said firstcontrol solenoid is in an OFF operational condition and said secondcontrol solenoid is in an ON operational condition.
 11. The hydraulicsystem of claim 10 wherein when said hybrid electric is in saidtransition mode, said first control solenoid is an OFF operationalcondition and said second control solenoid is in an ON operationalcondition.
 12. A hydraulic system for a hybrid electric vehiclecomprising: a sump containing hydraulic fluid; a main regulator valve; amain regulator by-pass valve; a mechanical pump constructed and arrangedin fluid communication with said sump and in fluid communication withsaid main regulator valve for delivering hydraulic fluid from said sumpto said main regulator valve; and an electric pump constructed andarranged in fluid communication with said sump and in direct fluidcommunication with said main regulator by-pass valve for deliveringhydraulic fluid directly from said sump to said main regulator by-passvalve, wherein the hybrid electric vehicle has three operational modesassociated with the hydraulic system, including an eMode, a transitionmode and a cruise mode, wherein said hybrid electric vehicle is in saidcruise mode, said first control solenoid is in an ON operationalcondition and said second control solenoid is in an ON operationalcondition.
 13. The hydraulic system of claim 12 wherein when said hybridelectric vehicle is in said cruise mode, all of the hydraulic fluidwhich is delivered from the sump to any of the valve of the hydraulicsystem is delivered by said mechanical pump.